Re: First build preparation and planning.
To answer your question # 4. Yes there is a way to take advantage of the multiple speeds. It is called a Shift Kit available at Sick bike Parts (look for advertisement around on the side of the forum). However, installing this kit requires an experience in building an MB. So it is up to you.
But if you prefer to go with a single sprocket. I highly recommend to get a sprocket adapter available at Creative Engineering (advertisement also on the side). I you like to make your build really easy then get his engine mount too. Enjoy!